Why? They are for leaning your bicycle against, as somebody did with the fourth urn back on the right. But what's that unusual short post with the hole in it near its top by the second urn on the left used for?

[Parking your horse. - Dave]

Just, WHY?

An elegantly accoutered but unpaved, partially-overgrown "avenue" with elegant building on one side and (possibly) nothing on the other: welcome to the fantasyland of Florida real estate, then and now.

[Indeed. The partly obscured sign at the entrance reads "[Burg]man and ***sden Real Estate." - Dave]

The best known Florida real-estate bubbles were in 1926 (see the Marx Brothers' 'Cocoanuts') and 2008 (see 'The Big Short'). Seabreeze--now a historic district of Daytona Beach--probably had the lucky timing to escape.

I have seen later postcards where a similar wide be-urned street was labeled "Ocean Boulevard" or "Seabreeze Boulevard."

"Seabreeze" was both the name of major street in Daytona Beach, and a separate town to the north, whose main street was named Ocean Boulevard (I think that's what we're seeing here, looking west). The two towns later merged, and Ocean Boulevard was renamed Seabreeze Boulevard, while Seabreeze Avenue seems to have been renamed Main Street. Questions?

A similar shot from further east on the grounds of the Clarendon Hotel - the town seemed to have something of a battlement fetish! - with the building three long blocks distant.

The two Wilmans' buildings that straddled Pine Grove Avenue

Okay, I’ll bite: what was the actual purpose of these urns? To be public planters? I wonder who would tend them. Nowadays they’d be filled with empty cigarette packs and butts.

Not there is any sign of it.

The street eclipsed only by the sand dune on the right.